Water jet boat thrust trimmer

ABSTRACT

In a water jet boat thrust source of the type comprising a water pump for generating a water jet, a steering conduit forming an exit nozzle through which the water is emitted, the steering conduit exit nozzle adjustable left and right in a horizontal plane for steering, and a steering lever arm system coupled to the exit nozzle for adjusting said exit nozzle left and right, the improvement including an adjustable trimming conduit interposed between the water pump and exit nozzle for adjusting the direction of thrust from the water jet in a vertical plane for trimming the boat, a second or trimming lever arm system coupled to the adjustable conduit for adjusting the conduit in a vertical plane upon actuation of the trimming lever arm system, and a friction coupling between the adjustable trimming conduit and the steering lever arm system so that upon adjustment of the trimming conduit in a vertical plane the steering lever arm system and exit nozzle move with the conduit maintaining the steering direction of the exit nozzle substantially constant during trimming. Alternatively, the trimming conduit is coupled downstream from the steering conduit so that the trimming conduit forms the exit nozzle.

United States Patent 1 Breslin 1 Sept. 4, 1973 1 1 WATER JET BOAT THRUSTTRIMMER [75] Inventor: Patrick W. Breslin, Watsonville,

Calif.

[73] Assignee: Custom Speed Marine, Inc., San

Jose, Calif.

22 Filed: Mar. 8, 1972 21 Appl. No.1 232,831

Primary Examiner-M. Henson Wood, Jr.

A tt0rney-Stephen S. Townsend, Thomas F. Smegal, Jr. et al.

[57] ABSTRACT In a water jet boat thrust source of the type comprising awater pump for generating a water jet, a steering conduit forming anexit nozzle through which the water is emitted, the steering conduitexit nozzle adjustable left and right in a horizontal plane forsteering, and a steering lever arm system coupled to the exit nozzle foradjusting said exit nozzle left and right, the improvement including anadjustable trimming conduit interposed between the water pump and exitnozzle for adjusting the direction of thrust from the water jet in avertical plane for trimming the boat, a second or trimming lever armsystem coupled to the adjustable conduit for adjusting the conduit in avertical plane upon actuation of the trimming lever arm system, and afriction coupling between the adjustable trimming conduit and thesteering lever arm system so that upon adjustment of the trimmingconduit in a vertical plane the steering lever arm system and exitnozzle move with the conduit maintaining the steering direction of theexit nozzle substantially constant during trimming. Alternatively, thetrimming conduit is coupled downstream from the steering conduit so thatthe trimming conduit forms the exit nozzle.

9 Claims, 5 Drawing Figures :aJssJas PATENTED SEP 4 I975 SHEET 1 BF 2FiG 2 sLvssL 185 PAIENTEDSEP 4191a SHEET 2 BF 2 FIG..?)

FIG. 4

1 WATER JET BOAT THRUST TRIMMER This invention relates to a new andimproved water jet boat thrust source and in particular to a systemarrangement for adjusting the drive source or thrust of a water jet boatin a vertical plane and to a method for trimming water jet boats.

The standard water jet boat drive source includes a pump such as animpeller pump and pump motor for generating a jet of water providingthrust and an exit nozzle through which the jet of water is emitted. Theexit nozzle is formed by a conduit adjustable left and right in ahorizontal plane and a lever arm system is provided which upon actuationadjusts the exit nozzle left and right for steering.

A principal object of the present invention is to pro vide a variety ofadjustable trimming conduit arrangements interposed and coupled betweenthe water jet pump and the steering conduit exit nozzle for adjustingthe attitude of the water jet up and down in a vertical plane therebyadjusting the direction of thrust in the vertical plane for trimming theboat. Alternatively, the trimming conduit is coupled downstream from thesteering conduit, itself forming an exit nozzle.

The capability of adjusting the water jet boat thrust in a verticalplane and of trimming the boat contemplated by the present inventionoffers a variety of features and advantages. The top speed range of theboat is increased because the wetted surface can be lessened with theexit nozzle and thrust adjusted in an upward direction to counteract lowpressure generated under the boat at high speeds which otherwise retainsa greater wetted surface against the water. On the other hand planingcan be achieved at lower speeds in the lower speed range by adjustingthe exit nozzle downwardly lifting the back up and out of the water andagain reducing the wetted surface. With the thrust properly adjusted ina vertical plane acceleration can be increased and resultingacceleration time decreased. Similarly, when towing objects andtransporting loads of different weight and at different speeds thehandling characteristics of the boat can be optimized by properadjustment of the vertical attitude of the thrust of the water jetexhaust. Adverse weather conditions can be overcome in operation of theboat by adjustment of the thrust up and down and safety of the boat inrough water is generally increased.

In order to accomplish these results the present invention generallycontemplates interposing and coupling between the water jet pump and thesteering exit nozzle of a water jet boat, means such as an adjustableconduit for adjusting the attitude of the exit nozzle up and down in avertical plane for trimming the boat. In one embodiment the adjustabletrimming conduit is coupled to the pump outlet by means of a pair ofpins forming a horizontal axis about which the adjustable trimmingconduit rotates in a vertical plane. The exit nozzle generally comprisesa second conduit coupled from the output of the first conduit by meansof a pair of pins forming a vertical axis about which the second conduitrotates in a substantially horizontal plane. Alternatively the steeringconduit and trimming conduit can be transposed so that the trimmingconduit is coupled downstream from the steering conduit forming atrimming exit nozzle.

The invention further contemplates providing a trimming lever arm systemcoupled to the adjustable trimming conduit and means for actuating thelever arm system for rotating the conduit about its horizontal axis in avertical plane. A steering lever arm system available as in the standardwater jet boat is coupled with the exit nozzle conduit for adjusting theexit nozzle in a horizontal plane about its vertical axis upon actuationof the steering lever arm system.

According to another aspect of the invention proper steering geometry ismaintained during vertical adjustment or trimming of the water jet boatthrust for the configuration in which the trimming conduit is coupledupstream from the steering conduit exit nozzle. Thus, an arrangement isprovided so that upon adjustment of the trimming conduit in a verticalplane for adjusting the thrust up or down to trim the boat, the steeringlever arm system coupled to the exit nozzle or steering conduit moves infixed relationship with the adjustable trimming conduit to maintain aconstant steering direction of the exit nozzle in the horizontal plane.In order to accomplish this result the steering lever arm system isfrictionally coupled with the adjustable trimming conduit.

In one embodiment the frictional coupling is provided by a tubular orcylindrical housing frictionally engaging and enclosing at least onelever arm on the steering lever arm system. The cylindrical or tubularhousing is fixed in stationary relationship to the adjustable trimmingconduit so that upon adjustment of the trimming conduit in a verticalplane the steering lever arm system and exit nozzle to which it iscoupled move with the cylindrical housing and the steering direction ofthe exit nozzle in the horizontal plane remains substantially constantduring trimming.

In the preferred embodiment, the adjustable trimming conduit means isinterposed between the water pump and exit nozzle for adjusting thedirection of thrust from the water jet in the vertical plane fortrimming the boat and comprises a ball joint having internal andexternal sides coupled by pins forming a horizontal axis. The internalside of the ball joint is fixedly coupled to the outlet of the waterpump for receiving the water jet and the external side of the ball jointis coupled at the horizontal axis for rotation relative to the internalside of the ball joint in a vertical plane. This movably mountedexternal side of the ball joint is coupled at its output side to theexit nozzle. A trimming lever arm system is coupled to the external sideof the ball joint for rotating the downstream side of the ball joint inthe vertical plane upon actuation of the trimming lever arm system.Finally, the steering lever arm system which is actuated for adjustingthe exit nozzle left and right in a horizontal plane for steering isfrictionally coupled to the external or downstream side of the balljoint so that upon rotation of the ball joint in a vertical plane thesteering lever arm system coupled with the exit nozzle moves with theball joint so that the direction of the exit nozzle in a horizontalplane. i.e., the steering geometry, remains constant during trimming.

Other objects features and advantages of the present invention willbecome apparent in the following spec ification and accompanyingdrawings.

FIG. 1 is a perspective view of a water jet boat thrust source inaccordance with the present invention.

FIG. 2 is a side view of the water jet boat thrust source with thetrimming conduit and exit nozzle adjusted to direct the thrust at anangle above the horizontal.

FIG. 3 is a side view of the water jet boat drive source with thetrimming conduit and exit nozzle adjusted to direct the thrust downwardat an angle below the horizontal.

FIG. 4 is a side cross-sectional view of the ball joint coupling foradjusting the direction of thrust up and down in a vertical plane.

FIG. 5 is an end cross-sectional view of the ball joint coupling.

Referring to the example illustrated in FIGS. 1 through 5 there isillustrated the rear portion of a water jet boat showing the thrustsource including an impeller pump 11 contained within bowl 12 fordeveloping a jet of water. The pump is driven by a marine engine orconverted automobile engine as is well known in the water jet boat art,housed within the hull of the boat. The water jet developed by pump 1 1is emitted through an exit nozzle 13 also of conventional design. Theexit nozzle 13 is coupled inside an intermediate conduit 14 by means ofa pair of vertical pins 15a and 15b which form a vertical axis aboutwhich the exit nozzle 13 can rotate left and right in a substantiallyhorizontal plane. The exit nozzle 13 is of smaller diameter than theintermediate conduit 14 so that there is leeway for rotation left andright about the axis formed by pins 15a and 15b. The exit nozzle 13 isthus used for left and right steering as is conventionally known andsteering is accomplished by means of a lever arm system 16 includinglever arm 17 coupled to the exit nozzle 13 through pin 15a andadditional lever arms 18 and 20 pivotally coupled in sequence. Lever arm20 is actuated by a conventional steering cable housed inside the boatand extending to the drivers seat for control by the driver. Inaccordance with the present invention the intermediate conduit 14 iscoupled at its upstream side to the outlet of water pump 11 through aball joint 21. In particular, the intermediate conduit 14 terminates atits upstream side in the external or outer side 22 of ball joint 21. Theoutlet from water pump 11 on the other hand terminates in the internalor inner side 23 of ball joint 21. In the illustrated example, theexternal outer side 22 of ball joint 2] is rigidly fixed to and forms aportion of the intermediate conduit 14 while the internal coupling 23 ofball joint 21 is rigidly fixed to the output of pump 11 and forms thepump outlet at the upstream side of the ball joint.

As shown in more detail in the cross-sectional views of FIGS. 4 and 5,the external side 22 of the ball joint terminates in a flange 24 whichis bolted to the intermediate conduit 14 forming an integral partthereof. The internal side 23 of ball joint 21 on the upstream sideterminates in flange 25 bolted to the outlet of bowl l2 and pump 1 1forming an integral part thereof. The relatively moving upstream anddownstream sides 23 and 22 respectively of ball joint 21 are coupledthrough a pair of horizontal pins 26a and 26b forming a horizontal axisabout which the intermediate conduit 14 can rotate relative to theoutlet of water pump 11 up and down in a vertical plane. By placing theinternal side 23 of ball joint 21 upstream from the external side 22,frictional impedance or obstruction of the water jet flow generated bypump 11 is minimized and the obtainable thrust maximized.

Up and down motion of the intermediate conduit 14 to which exit nozzle13 is coupled as previously described is controlled by means of thelever arm system 30 including lever arm 31 coupled to the external side22 of ball joint 21 at pin 26a and lever arm 32 which passes through anO-ring sealed hole 38 in the transom of the water jet boat and which iscontrolled by a conventional cable control system housed within the boatand extending to the driver's seat for control by the driver. Lever arm31 is pivotally coupled to lever arm 32. The lever arm system 30 isactuated by the cable control to rotate the intermediate conduit 14 towhich the exit nozzle 13 is coupled up and down in a vertical planeunder control of the operator.

It is thus seen that the thrust source illustrated in the example ofFIGS. 1 through 5 includes three relatively moving parts. Thus, thethrust source includes a water pump 11 in bowl 12 which generates awater jet exhaust through outlet 23; a first or intermediate trimmingconduit 14 coupled to the water pump outlet 23 by means of a pair ofhorizontal pins forming a horizontal axis about which the first orintermediate trimming conduit 14 rotates up and down in a verticalplane; and a second conduit or exit nozzle 13 coupled to theintermediate conduit 14 by means of a pair of vertical pins forming avertical axis about which the exit nozzle can rotate left and right in asubstantially horizontal plane. The rotation of the first and secondconduits in substantially vertical and horizontal planes respectively iscontrolled by means of separate first and second lever arm systems 30and 16 respectively, in turn actuated by separate cable controls underthe control of the driver or operator.

Appropriate frictional resistence is built in to the system at variouscoupling joints by, for example, O-ring seals such as O-ring seal 27within ball joint 21 as illustrated in FIG. 4.

The illustrated water jet boat thrust source includes the conventionalreversing attachment 40 for reversing the direction of thrust and acontrol cable 41 for lowering and raising the reversing attachment.

In operating the water jet boat thrust source described above it isapparent that if the operator of the boat actuates lever arm system 30for rotating the intermediate conduit 14 up and down in a vertical planethereby adjusting the thrust in a vertical plane for trimming the boat,the second lever arm system 16 used for steering the boat would normallybe effected because the relative distance between the exit nozzle andthe transom of the boat will change placing stress on the steering leverarm system 16 having the effect of turning the exit nozzle 13 left orright in one direction or the other changing the steering direction orcourse of the boat. At high speeds such unintended effects on thesteering can be dangerous and simultaneous adjustment of the trimminglever arm system 30 and steering lever arm system 16 by the driver wouldbe difi'icult at best. Therefore, in accordance with the presentinvention a novel coupling is provided in the steering lever arm systemin order to compensate for relative changes in the steering lever armsystem which are otherwise inevitable while trimming the boat.

To this end the lever arm 20 of steering lever arm 16 is enclosed withina tubular housing 35 which is pivotally coupled through arm 36 to theintermediate conduit l4 and in particular the external or downstreamside 22 of ball joint 21. The tubular housing 35 extends through anO-ring sealed hole 37 in the transom of the water boat for sliding backand forth through the hole 37 when the operator is trimming the boat.Thus upon actuation of lever arm 30 and rotation of intermediate conduit14 up and down in a vertical plane the tubular housing 35 extends intoand out of hole 37. The tubular housing 35 frictionally engages leverarm 20 of steering lever arm 16 so that the steering lever arm system iscarried with the tubular housing 35 which slides relative to the transomof the boat through hole 37 during trimming of the boat. This motion ofthe steering lever arm system with the tubular housing 35 in which it isfrictionally coupled, just compensates for the motion up and down of theexit nozzle 13 inevitably entailed during trimming of the boat so thatthe exit nozzle 13 retains a substantially constant direction in thehorizontal plane as far as left or right motion and the steeringdirection remains constant.

It is thus seen that the steering lever arm system 16 which is actuatedby a steering cable under the control of the driver for rotating theexit nozzle 13 left and right in a horizontal plane around the verticalaxis formed by pins 15a and 15b, is frictionally coupled to theintermediate or trimming conduit 14 through the tubular housing 35 whichencloses and frictionally engages the lever arm of steering lever arm16. The intermediate or trimming conduit 14 which rotates up and down ina vertical plane around a horizontal axis formed by pins 26a and 2617thus carries with it the exit nozzle 13 and the steering lever arm 16without relative movement of the steering lever arm system whichotherwise would effect the steering direction of the boat.

During the steering of the boat on the other hand the trimming conduitor intermediate conduit 14 under control of lever arm system 30 remainsfixed, and the steering lever arm 20 upon actuation of the steeringcable travels back and forth within the tubular housing 35 actuating theremainder of the lever arm system 16, turning the exit nozzle back andforth or left and right in a substantially horizontal plane forsteering.

The tubular housing 35 extends through the transom of the boat asufficient distance so that it always engages the rear transom throughhole 37 through the entire range of travel of the trimming conduit in anup and down direction. The steering lever arm 20 which extends entirelythrough the tubular housing 35 is coupled on the inside of the boat tothe steering cable in the conventional manner.

The ball joint 21 is designed to provide an optimum angular adjustmentup and down of 10 above and below the horizontal direction, the optimumangular direction required for trimming the boat, but can be constructedto permit a travel of up to 15 above and below the horizontal.

While the coupling between the trimming or intermediate conduit 14 andthe outlet of water pump 11 has been described in this example withreference to the preferred embodiment of a ball joint coupling, thecoupling could also be provided simply in the same manner in which theexit nozzle 13 is coupled to the intermediate conduit 14. Thus, theintermediate conduit 14 would simply be coupled inside the outlets frompump 11 and how] 12 by means of a pair of horizontal pins forming ahorizontal axis. The diameter of the intermediate or trimming conduit 14would in that case be smaller than the diameter of the outlet of pump 11in bowl 12 to provide some leeway in the rotational direction within theoutlet up and down in a vertical plane.

According to yet another embodiment the trimming conduit is coupled bymeans of a pair of horizontal pins forming a horizontal axis to thedownstream end of the steering conduit. in this arrangement the waterjet exits finally through the trimming conduit, the steering conduitcoupled between the water pump and trimming conduit. The latter iscontrolled by a separate flexible cable.

What is claimed is:

l. A water jet boat drive source comprising:

a water pump and means for driving said pump to generate a jet stream ofwater;

first conduit means coupled with the output from said water pump forguiding the water jet generated by said pump;

first lever arm system coupled to the first conduit means and means foractuating said lever arm for adjusting the attitude of said firstconduit up and down in a vertical plane for varying the direction ofthrust from said water jet in the vertical plane in order to trim theboat;

second conduit means coupled with the output of said first conduit meansfor guiding the water jet generated by said pump;

second lever arm system coupled to the second conduit and means foractuating said lever arm for varying said second conduit means right andleft in a horizontal plane in order to vary the direction of thrust ofthe water jet for steering; and

means for frictionally engaging and enclosing at least one of the leverarms of the second lever arm system in a tubular housing for movementwithin and relative to the tubular housing; during steering, saidtubular housing being coupled in fixed relationship to the first conduitmeans so that upon adjustment of the first conduit means in the verticalplane, the second lever arm system moves in fixed relationship with thetubular housing to maintain a constant steering direction of the secondconduit in a horizontal plane.

2. A water jet boat drive source as set forth in claim 1 wherein saidfirst conduit is coupled to the pump outlet by means of a pair of pinsforming a horizontal axis about which the first conduit rotates in avertical plane and wherein the second conduit is coupled to the outletof the first conduit by means of a pair of pins forming a vertical axisabout which the second conduit rotates in a substantially horizontalplane.

3. A water jet boat drive source as set forth in claim 1 wherein thesecond lever arm system is frictionally coupled to the first conduitmeans so that upon adjustment of the first conduit means in the verticalplane, the second lever arm system moves in fixed relationship tomaintain substantially constant steering direction in the horizontalplane.

4. A water jet boat drive source as set forth in claim 2 wherein saidfirst conduit comprises a ball joint having internal and external sidescoupled to the outlet of the water pump for receiving the water jet andthe external side of the ball joint coupled around said horizontal axisforrotation relative to the internal side of the ball joint in avertical plane for adjusting the direction of thrust from the water jetin a vertical plane for trimming the boat.

5. A water jet boat thrust source of the type comprising a water pumpfor generating a water jet and means for driving said pump, an exitnozzle through which the water jet is emitted, said exit nozzleadjustable left and right in a horizontal plane for steering the boat,and a first lever arm system coupled to said exit nozzle for rotatingsaid exit nozzle in a horizontal plane upon actuation of said lever armsystem, the improvement comprising:

conduit means interposed and coupled between the water pump and exitnozzle for adjusting direction of thrust from the water jet in avertical plane for trimming the boat;

second lever arm system means coupled to the conduit means for adjustingthe attitude of said conduit means up and down in a vertical plane forvarying the direction of thrust from the water jet in a vertical planeupon actuation of the second lever arm system;

and means frictionally coupling the first lever arm system to theconduit means so that upon adjustment of said conduit means in avertical plane the first lever arm system and exit nozzle move with theconduit means and the steering direction of the exit nozzle in ahorizontal plane remains substantially constant during trimming.

6. A water jet boat thrust source as set forth in claim 9 wherein theconduit means comprises a ball joint having internal and external sidescoupled by hinge means forming a horizontal axis, the internal side ofthe ball joint fixedly coupled to the outlet of the water pump forreceiving the water jet and the external side of the ball joint coupledaround said horizontal axis for rotation relative to the internal sideof the ball joint in a vertical plane, the external side of the balljoint coupled to the exit nozzle.

7. A water jet boat thrust source of the type comprising a water pumpfor generating a water jet and means for driving said pump, an exitnozzle through which the water jet is emitted, said exit nozzleadjustable left and right in a horizontal plane for steering, and afirst lever arm system coupled to said exit nozzle for rotating saidexit nozzle in a horizontal plane upon actuation of said lever armsystem, the improvement comprising:

conduit means interposed between the water pump and exit nozzle foradjusting the direction of thrust from the water jet in a vertical planefor trimming the boat comprising a ball joint having internal andexternal sides coupled by pins forming a horizontal axis, the internalside of the ball joint fixedly coupled to the outlet of the water pumpfor receiving the water jet and the external side of the ball jointcoupled around said horizontal axis for rotation relative to theinternal side of the ball joint in a vertical plane, the external sideof the ball joint coupled to the exit nozzle;

a second lever arm system means coupled to the extemal side of the balljoint for rotating the downstream side of said ball joint up and down inthe vertical plane upon actuation of said first lever arm system;

and a tubular housing fixed to the conduit means, said cylindricalhousing frictionally engaging and enclosing at least one lever arm ofthe first lever arm system whereby upon adjustment of the conduit meansin a vertical plane the second lever arm system and exit nozzle movewith the cylindrical housing so that the steering direction of the exitnozzle in a horizontal plane remains substantially constant duringtrimming.

8. A water jet boat thrust source of the type comprising a water pumpfor generating a water jet and means for driving said pump, an exitnozzle through which the water jet is emitted, said exit nozzleadjustable left and right in a horizontal plane for steering the boat,and a first lever arm system coupled to said exit nozzle for rotatingsaid exit nozzle in a horizontal plane upon actuation of said lever armsystem, the improvement comprising:

conduit means adapted to cooperate with said water pump and exit nozzlefor adjusting direction of water thrust from the water jet in a verticalplane for trimming the boat;

second lever arm system means coupled to the conduit means for adjustingthe attitude of said conduit means up and down in a vertical plane forvarying the direction of thrust from the water jet in a vertical planeupon actuation of the second lever arm system;

and means frictionally coupling the first lever arm system to the secondlever arm system so that upon adjustment of said conduit means in avertical plane the first lever arm system and exit nozzle move with theconduit means and the steering direction of the exit nozzle in ahorizontal plane remains substantially constant during trimming.

9. A water jet boat thrust source in accordance with claim 8 whereinsaid conduit means is interposed and coupled between said water pump andexit nozzle.

1. A water jet boat drive source comprising: a water pump and means fordriving said pump to generate a jet stream of water; first conduit meanscoupled with the output from said water pump for guiding the water jetgenerated by said pump; first lever arm system coupled to the firstconduit means and means for acTuating said lever arm for adjusting theattitude of said first conduit up and down in a vertical plane forvarying the direction of thrust from said water jet in the verticalplane in order to trim the boat; second conduit means coupled with theoutput of said first conduit means for guiding the water jet generatedby said pump; second lever arm system coupled to the second conduit andmeans for actuating said lever arm for varying said second conduit meansright and left in a horizontal plane in order to vary the direction ofthrust of the water jet for steering; and means for frictionallyengaging and enclosing at least one of the lever arms of the secondlever arm system in a tubular housing for movement within and relativeto the tubular housing during steering, said tubular housing beingcoupled in fixed relationship to the first conduit means so that uponadjustment of the first conduit means in the vertical plane, the secondlever arm system moves in fixed relationship with the tubular housing tomaintain a constant steering direction of the second conduit in ahorizontal plane.
 2. A water jet boat drive source as set forth in claim1 wherein said first conduit is coupled to the pump outlet by means of apair of pins forming a horizontal axis about which the first conduitrotates in a vertical plane and wherein the second conduit is coupled tothe outlet of the first conduit by means of a pair of pins forming avertical axis about which the second conduit rotates in a substantiallyhorizontal plane.
 3. A water jet boat drive source as set forth in claim1 wherein the second lever arm system is frictionally coupled to thefirst conduit means so that upon adjustment of the first conduit meansin the vertical plane, the second lever arm system moves in fixedrelationship to maintain substantially constant steering direction inthe horizontal plane.
 4. A water jet boat drive source as set forth inclaim 2 wherein said first conduit comprises a ball joint havinginternal and external sides coupled to the outlet of the water pump forreceiving the water jet and the external side of the ball joint coupledaround said horizontal axis for rotation relative to the internal sideof the ball joint in a vertical plane for adjusting the direction ofthrust from the water jet in a vertical plane for trimming the boat. 5.A water jet boat thrust source of the type comprising a water pump forgenerating a water jet and means for driving said pump, an exit nozzlethrough which the water jet is emitted, said exit nozzle adjustable leftand right in a horizontal plane for steering the boat, and a first leverarm system coupled to said exit nozzle for rotating said exit nozzle ina horizontal plane upon actuation of said lever arm system, theimprovement comprising: conduit means interposed and coupled between thewater pump and exit nozzle for adjusting direction of thrust from thewater jet in a vertical plane for trimming the boat; second lever armsystem means coupled to the conduit means for adjusting the attitude ofsaid conduit means up and down in a vertical plane for varying thedirection of thrust from the water jet in a vertical plane uponactuation of the second lever arm system; and means frictionallycoupling the first lever arm system to the conduit means so that uponadjustment of said conduit means in a vertical plane the first lever armsystem and exit nozzle move with the conduit means and the steeringdirection of the exit nozzle in a horizontal plane remains substantiallyconstant during trimming.
 6. A water jet boat thrust source as set forthin claim 9 wherein the conduit means comprises a ball joint havinginternal and external sides coupled by hinge means forming a horizontalaxis, the internal side of the ball joint fixedly coupled to the outletof the water pump for receiving the water jet and the external side ofthe ball joint coupled around said horizontal axis for rotation relativeto the internal side of The ball joint in a vertical plane, the externalside of the ball joint coupled to the exit nozzle.
 7. A water jet boatthrust source of the type comprising a water pump for generating a waterjet and means for driving said pump, an exit nozzle through which thewater jet is emitted, said exit nozzle adjustable left and right in ahorizontal plane for steering, and a first lever arm system coupled tosaid exit nozzle for rotating said exit nozzle in a horizontal planeupon actuation of said lever arm system, the improvement comprising:conduit means interposed between the water pump and exit nozzle foradjusting the direction of thrust from the water jet in a vertical planefor trimming the boat comprising a ball joint having internal andexternal sides coupled by pins forming a horizontal axis, the internalside of the ball joint fixedly coupled to the outlet of the water pumpfor receiving the water jet and the external side of the ball jointcoupled around said horizontal axis for rotation relative to theinternal side of the ball joint in a vertical plane, the external sideof the ball joint coupled to the exit nozzle; a second lever arm systemmeans coupled to the external side of the ball joint for rotating thedownstream side of said ball joint up and down in the vertical planeupon actuation of said first lever arm system; and a tubular housingfixed to the conduit means, said cylindrical housing frictionallyengaging and enclosing at least one lever arm of the first lever armsystem whereby upon adjustment of the conduit means in a vertical planethe second lever arm system and exit nozzle move with the cylindricalhousing so that the steering direction of the exit nozzle in ahorizontal plane remains substantially constant during trimming.
 8. Awater jet boat thrust source of the type comprising a water pump forgenerating a water jet and means for driving said pump, an exit nozzlethrough which the water jet is emitted, said exit nozzle adjustable leftand right in a horizontal plane for steering the boat, and a first leverarm system coupled to said exit nozzle for rotating said exit nozzle ina horizontal plane upon actuation of said lever arm system, theimprovement comprising: conduit means adapted to cooperate with saidwater pump and exit nozzle for adjusting direction of water thrust fromthe water jet in a vertical plane for trimming the boat; second leverarm system means coupled to the conduit means for adjusting the attitudeof said conduit means up and down in a vertical plane for varying thedirection of thrust from the water jet in a vertical plane uponactuation of the second lever arm system; and means frictionallycoupling the first lever arm system to the second lever arm system sothat upon adjustment of said conduit means in a vertical plane the firstlever arm system and exit nozzle move with the conduit means and thesteering direction of the exit nozzle in a horizontal plane remainssubstantially constant during trimming.
 9. A water jet boat thrustsource in accordance with claim 8 wherein said conduit means isinterposed and coupled between said water pump and exit nozzle.